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Codeforces 1042F.cpp
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Codeforces 1042F.cpp
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#include <bits/stdc++.h>
#define pb push_back
#define pf push_front
#define pob pop_back
#define fp first
#define sp second
#define mp make_pair
#define ins insert
#define uEdge(u, v) g[u].pb(v), g[v].pb(u)
#define uwEdge(u, v, w) g[u].pb({v, w}), g[v].pb({u, w})
#define dEdge(u, v) g[u].pb(v)
#define dwEdge(u, v, w) g[u].pb({v, w})
#define BOOST ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define minHeap int, vector<int>, greater<int>
using namespace std;
typedef long long int lli;
typedef pair<int, int> pii;
vector<int> g[1000010];
multiset<int> dsu[1000010];
int k;
lli gcd(lli a, lli b){
if(b == 0) return a;
a%=b;
return gcd(b, a);
}
lli lcm(lli a, lli b){
return (a*b)/gcd(a, b);
}
int binsearch(int n, lli arr[], lli sum){
int l = 0, r = n-1, mid;
while(l<=r){
mid = (l+r)/2;
if(arr[mid]==sum) return mid;
if(arr[mid]<sum) l = mid+1;
else r = mid-1;
}
return -1;
}
void DFS(int u, int p, int d){
if(p && g[u].size()==1){
dsu[u].insert(d);
return;
}
int bigc = -1, dk, dki_val;
for(auto v : g[u]){
if(v==p) continue;
DFS(v, u, d+1);
if(bigc == -1 || dsu[v].size() > dsu[bigc].size()) bigc = v;
}
swap(dsu[bigc], dsu[u]);
for(auto v : g[u]){
if(v==p || v==bigc) continue;
for(auto di : dsu[v]){
dk = d+k-(di-d);
auto dki = dsu[u].upper_bound(dk);
if(dki==dsu[u].begin()) dsu[u].insert(di);
else{
--dki;
dki_val = *dki;
dsu[u].erase(dki);
dsu[u].insert(max(di, dki_val));
}
}
}
}
int main(){
int n, u, v;
scanf("%d %d", &n, &k);
for(int i=0; i<n-1; i++) scanf("%d %d", &u, &v), uEdge(u, v);
for(u=1; u<=n; u++){
if(g[u].size()>1){
DFS(u, 0, 0);
printf("%d\n", dsu[u].size());
break;
}
}
return 0;
}